Security systems are often installed within and around buildings such as commercial, residential, or governmental buildings. Examples of these buildings include offices, hospitals, warehouses, schools or universities, shopping malls, government offices, and casinos. The security systems typically include components such as access control systems, surveillance cameras, image analytics systems, network video recorders (Milks), security alarm panels and devices connected to those panels to list a few examples.
The security devices of the security alarm panels include motion sensor devices and relays, for example. Motion sensor devices can detect intrusions and relays can detect door or windows being opened. These devices are used to detect unauthorized access to the premises, and send indications of the intrusions to the security panel.
Access control systems in buildings, for example, are principally concerned with physical security and the selective access to, restriction of, and/or notification of access to an area or other resource. In a business setting, for example, each employee or other individual can have different levels of security access based on their job function, and the access control system can enforce these access policies at the level of the individual access control readers. For example, an accounting employee may obtain access to a workplace building via an access control reader located at the perimeter of the building. Once inside, however, the same employee is not authorized to access an engineering area or physical plant maintenance area of the building, the access to which is controlled by access control readers that restrict access to authorized individuals typically having only engineering and plant maintenance job functions, respectively.
The main components of the access control systems are access control readers and possibly door controllers. The access control readers are installed near access points, such as doors or hallways or elevators, and enable presentation of credentials to obtain access to restricted areas such as buildings or areas of the buildings. Typically, individuals interact with the access control readers by swiping keycards or bringing contactless smart cards within range (approximately 2-3 inches or 5 centimeters) of the reader. More recently, frictionless access control systems have become common. In these systems, user devices, such as smart phones or wireless fobs, transmit credentials to nearby readers. The access control readers read the credential information of the users and validate the information possibly by reference to a verification database maintained by an access controller, which confirms the credentials and determines if the individuals are authorized to access the restricted areas. If the individuals are authorized, then the access control readers might signal door controllers to unlock doors or to not generate alarms, in examples.
The access control readers can often be controlled in different ways and can typically receive input power in different ways. In one example, a keycard access control reader can be both controlled by and receive its source of input power from a dedicated output interface/control line of the access controller. For this purpose, the access controller can provide a switched source of 12 VDC or 24 VDC to each keycard access control reader via the dedicated output/control line. In another example, a networked access control reader can receive its control signals over an open, internet protocol (IP) network such as a Local Area Network (LAN) and also has an independent source of input power. In yet another example, a smart card access control reader is controlled by an access controller but relies on an external power module as its source of input power. Here, the power module is also controlled by the access control controller and provides a switched source input power such as 12/24 VDC to the smart card access control reader.